Scalloped edge on settling tank for grit blasting



March 3, 1964 SCALLOPED EDGE oN SETTLING TANK FOR GRIT BLASTING R. G. MILLHISER ETAL 2 shets-sheet 1 March 3, 1964 R.G.M|1 LH|sER ETAL 3,122,363

SCALLOPED EDGE ON SETTLING TANK FOR GRIT BLASTING Filed May 23, 1961 2 Sheets-Sheet 2 'gli/113111111111415'.

F/a/4 F/6-5 United States Patent O 3,122,563 SCALLPEE EDGE N SETTUNG TANK FSR GRH" BLSTNS Rehert G. Millhiser and Nicholas E. Panaica, Detroit, and

Willard Lewis Sohnson, Southiield, Mich., assignors to Ajem Laboratories, lne., Livonia, Mich.

Filed May 23, i961, Ser. No. 125,609 l d Claims. (3. 5.1-8)

This invention relates to devices for separating unwanted line particles, dirt, etc. and excess liquids from suspensions carrying particulate solids, and to the processes of such separation.

More particularly, this invention relates to deburring and abrading apparatus of the type wherein smoothing, trimming, or, in general, surface reforming of manufactured parts is eifected by hard particles entrained in high velocity liquid sterams. Apparatus of this general type for deburring, peening and/or abrading is shown, for example, in the copending Emil Umbricht et al. patent application US. Serial No. 9,9l0 iiled on February 19, 1960. For sake of brevity we shall refer to suc-h hard particles, whether sharp ahrasive grains or smooth shot or smaller particles, etc., for surface reforming by the term grit As fully described in the above-identied patent application, the grit is suspended in a liquid medium contained in a hopper-like tank, or sump, conveniently positioned. The grit gravitates toward the bottom of the sump gradually being concentrated to a slurry; and there it is entrained in an ejector by the action of a liquid jet and thus accelerated upward through a blast tube, extending to the surface of the liquid mass and is directed into a blasting chamber and against the manufactured part positioned therein.

Because high pressure liquid jets are used to drive the rit against the surfaces being treated, Vand for washing away residual grit from the parts and the apparatus, it is necessary to separate excess liquid before re-using the grit. Moreover, since the treatment with the grit knocks and scrapes o from the treated parts small pieces and particles of metal, mold or core sand, scale, dirt, etc., these are with the liquid which drain back from the blasting chamber. Also slimes, oils, colloidal particles, detergents and surface coating materials of various kinds are scoured off from the parts during treatment and Washed away in the drain-back. All these things complicate the separation problem, and some of them have ilotation effects which tend to carry off in foam valuable grit which is desired `for reuse.

lt is, of course, desirable to collect the drain-back directly as it falls from the part being treated and the chamber around it; but since washing and separation of the grit are necessary, the recovered material has had to be taken od for such treatment. When the grit used is abrasive, every transfer of this kind which requires pumping or rapid movement is a source of deterioration of the apparatus and the grit.

The present invention is concerned with improving the apparatus for reclaiming and returning the grit for re-use. lt is particularly concerned with providing means for separating, reconditioning and returning the grit, which will be so eldcient and compact that those yfunctions can be accomplished in the zone beneath the blasting Zone.

With this object in View, we provide a liquid-return system having a sump, sloping-surfaces leading to the sump, and weir edges, all located to collect the drain-back material, i.e., the entraining liquid, the grit, and superfluous matter. The drain-back into the sump creates an overilow; and we control the conditions of the overflow so H that 1t effects a separation of waste matter, with superduous liquid, from the grit and a part of the liquid, which 3,l22,863 Patented Mar. 3, 1964 are retained in the sump and re-used. To this end we provide a level Weir edge around the sump, of such length as to limit the depth and velocity of the overiiow. Thus we carry o the liner dirt and Waste. Advantageously, we also provide baiies adjacent to the weir to control the low to the -weir in such geometrical design and arrangement that substantially only the excess liquid and waste solids reach the -weir for overflow, while the less readily suspended solids remain to settle in the sump and serve as surface reforming grains for further operation of the process.

Because of its more rapid settling rate and the design of our apparatus, the grit is below the depth of theweir edge in the overflowing liquid before it reaches-the Weir edge and theretfore continues to settle into the. sump.y Thus the supply of suitable surface reforming grains in the sump is continuallyl replenished by this drain-back material, and is continually cleaned of unwanted material. The action just described is related to velocity of flow of liquid across the sump to the overiow edges and' especialy its velocity at the weir edge.

We have `found that eicient reclaiming vand re-use of grit in such operationsrequires overflowing the excess liquid uniformly along a sufficient weir length to keep. aA uniformly shallow depth, and low velocity of flow inthe escaping liquid, whereby to insure a positive separation of the solid matter to be retained in the apparatus for reuse, but to carry oli the dirt.

An object of this invention, therefore, is to provide. a rate and depth of overow of the excess liquid overV a weir edge which, -with due regard for any turbulence introduced within the body of liquid will provide :for washing oit the dirt and settling back the ygranular blasting, material suitable lfor reuse. Becauseoithe velocity of liquid ilow required for effective wet blast treatments, this separation requires an increase in the length of Weir edge beyond that of a suitable sump or storage tank. It is an object of our invention to provide this length Without excessive increase in size and cost of the apparatus.

Another object of this invention is to condition the owV of excess liquid toward a Weir edge so as to 'favor sedi-r mentation of the heavier matter suspended therein.

Accordingly, we have set forth below an embodiment of our invention wherein we achieve these objects by a novel weir and advantageously with a novel baffle-system each of which ai'lords striking improvement and which together" combine to give extraordinary eciency andeffectiveness in operation. ln accordance with one aspect of this invention, a bathe arrangement is positioned adjacent to and within the Weir edge around that portion of the sumpinto which the drain back material is received. This baille arrangement functions, in eiect, to control turbulence in the vicinity of the weir and to introduce -local `flow patterns which facilitate separation oi suspended solids. Thus the excess liquid is conditioned so as to overflow uniformly along the entire length of the Weir and the desired separa.- tion of matter suspended therein is eected. Also, this excess liquid as'it flows through the novel bale arrange-- ment toward the Weir, undergoes abrupt changes in liow-Y direction whereby the sedimentation ofsuspended mattertherein is acceleated.

To control the overflow rate of the excess liquid so as f. to gauge the line between separation'and retention Vof the suspended solids, a series of pocket-like extensions are provided along the Weir edge which both increase the effective weir length of `the-system and provide quiescent bodies of liquid adjacent these extended edges. These pocket-like extensions may bev in open communication with the body of liquid, but we rind it advantageous to have balles between to keep any rapid liow away from the Weir edge, eg., to allow liquid to enter into these.` extensions well below the Weir level and to fan out to the i edges. The Weir edges of the pocket-like extensions are disposed in the same plane as the weir edges between them so as to be in eiect continuous therewith, whereby the excess liquid overilows uniformly and at a reduced rate along the eilective Weir length. Accordingly, the sedimentation rate of the suspended matter is increased and also the velocity of the overilow liquid is uniformly reduced along the eiective weir length; and the elciency of reclaiming the grit is greatly increased.

In this specification and the accompanying drawings We have shown and described a preferred embodiment of the invention and certain modifications and alternatives; it will be understood, however, that these are given for purposes of illustration in order that others skilled in this art may fully understand the invention and the principles thereof and its application to practical use so that they can modify it and adapt it in various forms, each as may be best suited to the conditions of the particular use.

In these drawings:

yFIGURE 1 is a view in longitudinal vertical section taken on line 1 1 of FIGURE 2;

FIGURE 2 isa view in horizontal section taken on line 2 2 of FIGURE 1;

FIGURE 3 is a fragmentary isometric sectional View of an apparatus embodying this invention;

FIGURE 4 is a detail view in section taken along the line 4-4 of FIGURE 2; and

FIGURE 5 is a sectional view of one oi' the pocket-like extensions in accordance with this invention.

` Referring to these drawings, the apparatus shown comprises a blasting chamber 1 and flushdown or washing chamber 3 for deburring parts 4 transported longitudinally therethrough by conveyor means, not shown. In the blasting chamber 1 indicated in FIG. l such manufactured parts 4 are treated for surface re-forming by the impingement thereon of surface-reforming grains entrained in high velocity liquid streams. The ilushdown chamber 3 is adapted for washing the part, after such surface treatment, by high velocity, clear liquid streams to remove any residues from the blasting treatment, eg., surface reforming grains, mold material, core sand, loosened scale or ilakes, etc. The present invention makes it feasible to return to the sump 5 the wash liquid and the grit thus Washed oil, and thus to reclaim the grit and to utilize the excess wash liquid to clean the reclaimed grit.

The parts 4 to be thus treated are carried successively through the blasting chamber 1 and the ilushdown chamber 3. For example, the individual parts 4 (shown in FIGURE 3 as a brake drum) may suspend from an endless chain conveyor (not shown) extending through these chambers by a holding means 3.

A water-shed under the blast and wash chambers 1 and 3 comprises a sump 5 which serves as a settling tank e.g., of rectangular shape, and a sloping gutter 7. The sump 5 is made of a number of plate members welded at their edges, or otherwise joined, so as to converge downwardly in hopper-like fashion toward a number of blasting manifolds 9; and the gutter 7 is likewise formed of plates joined at their edges to the edges of sump 5.

The blasting manifolds 9 are aillxed to a base plate 14 of sump 5. Pairs of inner plate members are angularly positioned in the base of sump 5 and joined to each other and tothe sloping sides of the sump, e.g., by welding abutting edges so as to complete hopper-like sections for each of the blasting manifolds 9. The blasting manifolds 9 are disposed beneath the blasting chamber and one end 16 of the water-shed extends beneath the ilushdown chamber 3.

Each manifold 9 is provided with several jet orifices or nozzles 19; and alined above these, respectively, are the blast tubes 20 (see FIGURE 3, where for purpose of clarity only one tube 2G is shown) which, combined with the nozzles 19, constitute an eductor to suck in the settled slurry from the bottom of the sump and entrain it in the high velocity jet from nozzle 19. The spacing between a blast tube 2i) and a nozzle 19 is adjusted to give the desired eductor action. The resulting blast is protected from the liquid in sump 5 by blast tube 2G with any extension thereof, as desired, such as the casing 21. A liquid-conduit system, for supplying clean liquid under pressure to the manifolds 9 is illustrated at 22. This system comprises a pump 23 connected through the respective manifolds 9 with the blasting nozzles 19. The pump 23 is ordinarily a high pressure, high capacity pump and is immersed in a clear liquid storage tank 25.

A second branch of the liquid conduit system 22 goes to the manifolds 9 for the washing jets 29 in the ilushdown chamber 3. These jets are directed against articles positioned in the path of the jet after blasting with grit in chamber 1. The run-back from this wash falls into the end portieri of the sump where any grit and heavier particles washed back gravitate toward and along its sloping bottom. A rim 17 on sump 5 and on pocket-like apendages 18 serves as an overilow Weir with its extensive edge all at one level.

If enough peripheral space is provided in the sump to bring the liquid to a quiescent ilow and allow the grit to settle out before it reaches the vicinity of the weir 17, a

simple weir edge on the tank could be suillcient, but by the present invention, the area requirement for such settling is greatly reduced and eiiiciency increased.

In accordance with the principles of this invention, a baille structure (see FIGURES 3 and 4) is arranged about that portion of the sump into which the drain-back material is received. This baille structure, as shown, comprises a plurality of angularly related I'lat members 34, 35, 35, 37 and 3S secured in the peripheral part of sump 5. The bailles 34, 35, 36, 37 and 3S are alternately inclined so that each is directed toward, and substantially perpendicular to the plane of, the next outwardly-adjacent baille. In addition, the upper edges of the batlles 35 and 37 extend a little above the Weir level, while their lower edges extend suillciently below the weir level to assure that the liquid level between these bailles will overow the upper edges at a level above that of the Weir. The effect of these baflles is that the liquid ilowing outwardly is forced to overilow the bailles 35 and, in doing so, tends to deilect downwardly the grit particles, which have radial momentum tending to carry them outwardly as the liquid rises. Again at the baffle 36, both the liquid and any entrained particles tend to flow up onto the ramp surface of 36. The upper edge of 36 is formed as a lip to prevent the liquid from overilowing. As this liquid laps up on the ramp, like tidal water rising on a beach, it creates an undertow ilowing back down the ramp and this again gives a momentum to entrained grit particles, which tends to throw it down onto the upper surface of the baille 3S, while the liquid again reverses its ilow and rises between bailles 36 and 37. At 37 again, as at 35, the radial momentum of any entrained grit particles carries them against the sloping underside of the baille and thence downward, while the liquid overows the top edge of the baille 37 and eventually runs on over the Weir edge 17.

The lower edges of the members 34 and 36, on the other hand, extend to a lesser depth below the weir level and at an angle directed downwardly into the ilow, thus functioning as a skimmer device to skim off any foam, and hold it in contact with the flowing liquid and give it opportunity to break and drop any grit which it has iloated.

These multiple bailles at the surface of the liquid also smooth out any waves which might be formed by the blasting action and which, if not intercepted, might cause irregular overflow.

The upper edges of the members 34 are juxtapositioned with, and extend slightly above the level of, the lower edges 47 of the blasting chamber 1 and, likewise, of ilushdown chamber 3. Thus, the inner rectangular bailles 34, in eilect, form a pyramidal bottom section on the blasting chamber 1 and the ilushdown chamber 3, extending below the weir level. This allows room for the bailles 34-37 s,122,ees

with lesser overall dimensions of the sump 5. The ballles 34 may, however, be outside the-walls of chambers l and 3, especially if the chamber wall is extended downward so that its bottom edge 47a is below the liquid `level in the sump.- This is shown for example in'FlGURE 4, in which the position of the bottom ot' 47 in the otherrgures is indicated by broken lines for comparison.

The baille 35 is spaced at its lower edge from the peripheral wall of sump, leavinfy a narrow passage 49 which need only be largeV enough to pass the normal llow oi excess-liquid and waste solids carried thereby.

The internal baille 3S positioned beneath the passage gathers the lliquid'ilow-to the outlet passage 49 and protects against a turbulent washing ofthe sloping wall 6 onto which grit may have settled.

In the operation of the device shown and described above, the sump 5 is filled with a suitable blasting and washing liquid, for example, water or an aqueous solution ot surface treating chemicals, such as detergents, rust inhibitors, passivating agents, detoamants and-the like. The grit, eg., malleable'iron grit of the grade-.known in the trade as G40, is dumped into the sump so that it settles into the bottom areas aroundthe jets 19.- With the articles to be treated suitably supported over the blast tubes Eil-2l, the pump 23 is operatedv to supply the liquid under relatively high pressure to the manifolds 9.V This liquid, escaping through nozzles 19, entrains the grit byejector action into a blast directed up through the blast tubes 2li intotthe chambers 1 and against the articles being treated. LikewiseV in chamber 3 a jet ofV the liquid is directed against the articles held above it, which have already been treated by the grid blasting in chamber 1.

The liquid and grit iall back from this treatment into the sump 5, carrying with it a certain amount of dirt, sand, scale, oil, etc., removed from the surfaces of the articles being treated. As this fall-back material includes excess liquid used in the llush chamber 3, there must be an overflow equal tothe excess. ll this were merely allowed to overilow the edge of a simple rectangular sump, the overilow velocity would carry grit over the edge with the waste-liquid with resulting nuisance in the disposal facilities and expense for replacing it with fresh grit. A larger sump reduces the velocity of the overfiow,'but such large sumps are expensive in themselves and occupy expensive plant area.

ln the preferred embodiment illustrated this rate oi llow is attained by increasing the length or Weir edge by making a tortuous form as a result of the numerous pocket-like extensions i3, each about a four inch square. Wider shallow pockets can be used where less weir length is required and narrow, longer and deeper pockets where greater length of weir is needed. Sinuous Weir edges can be provided instead of such rectangular tortuous form, or a meandering edge or saw-tooth form.

The liquid flowing from the central area in the example shown, within the baille'34 toward the Weir edge i7 must ilrst pass under the innermost baille 34- (and also under the bottom edge 47u01 the chamber l, if it is arranged as shown in full lines in FG. 4), then it spreads radially and upward into the space beyond 'the baille 34 from which the liquid overilows the top of baille 35. Entrained grit, however, which has greater momentum in the radial direction, will tend to strike and be deflected downward by the lower surface of the battle 35 meanwhile gradually settling through the liquid toward the bottom of the sump 5.

It will be noted that the liquid level as it overflows the baille 35 is higher than the Weir level, i.e., the reversal of ilow which occurs and the very narrow gap at the bottom of baille 35 are suilicient to hold back the liquid until it reaches a substantial head.

Beyond the baille 35 the liquid again spreads out radially and downwardly. Some or" the entrained grit particles settle onto the top surface oL 35 and into the area between the bottom edge of 36 and the top of 35. Another portion oi the grit is carried up over the sloping face of baille 36 where it laps the surface and turns back down to create an` undertow, so that at the bottom of the'baille 56 the liquid and entrained grit particles are flowing toward thetbaihe 35. Thus the entrained particles are again given a momentumecausing'them to travel downward toward vbaille 35 and along its surface while the-liquidagain reverses its ilow to spread upwardly and outwardly in the `area betweenV bailles 36` and 37. Here again, as with^ballle 35,

the outward momentum of entrained grit tends'to rcarryA it against the underside of baille', where it is deflected downwardly and settles toward the slot 49 at the-bottom f of baille 35, whilethe-liquid voverilows baille37 and falls` into the ilnal settling area between baille 37 andthe weir` 17 and eventually overflows into thetrough 7 Here againthe diversion from the flow-down along the top surface of baille 3'7 to overilow the weir 17 causes any remaining entrained grit to be carried by its momentum toward the slot 53. rlfhe grit collects'ilrst in the trough `formed by bailleV 37V and thenin the trough behind baille- 37 and gradually settles through slots 53-and `@and along baille 3S and down into the sump.

ln a preferred example as set forth, the lower edge of the baille 35 is 1A; inch from `the vertical-peripheral wall of'thetsump` and Mi inch frornthe top -of thebaille 33.`

lnthis instance, the baille 3S is about 30 above the sloping bottom 6 of the sump 5 yand about 20 downward slopeV from the horizontall Bail'leSin this instance is about 3 wide, baille 35 about l0 wide, ballle 36 about 31/2" wide and baille 37 about 2%" wide. 3d,l 35, 36 and 37 all slopeV at about 45.

rlhe gap 49 is dimensioned to restrict the ilow-theref through so as to avoid Washing upward from the gap.v

Thus,'the outward ilow causes a small rise in the liquid level at the upper edge of the baille 35 and likewise with the baille 37. This results ina thin layer of the-lightest liquid (i.e., that mostfree from the grit) overilowing' theupper-edges of these baiiles.V The intermediate bafiles 35 and 36 force reversals lin the direction of Vilow as described above so as to increase the separating action.

The grit used for surface-reforming is normally suspended in a liquid in the `sump 5. Due to the'hopperlike configuration of the sump, the grains of the grit gravitate toward an eductor'device consisting of the jets 19 and blast tubes 'Z0-2l, by which theyA are entrained inthe' highvelocity liquid streams emanating from the nozzles i9 and blasted against thearticles 4- held above in chamber 1. The larger section 21 of the blast tubes serves to hold back the liquid in the sump and keep a space for the blast'to pass without interference. Liquid is directed under pressure to each of nozzles 19 and 29 in iet-lil e fashion. (The blast tubes` 2,9;21 are omitted from FlGURES l and 2 for clarity, but one is shown in VFIGURE 3.)1

Accordingly, the grit impinges4 on the articles positioned in, or being transported through,V the blasting.

chamber l1, with suillciently high energy to e'iect the desired reforming process.V

Duringoperation, solid matter suspended in the -ilowback liquid is continuously settling out at a rate which is a lfunction of its size, density, and other characteristics. The sedimentation'rate of the suspended matter, however, is advantageously increased by ilowing the excess liquid through the novel baffle arrangement and thus subjecting it to abrupt changes in llow direction which are transverse to its normal, lateral ilow pattern toward the weir edge i7. For example, on passing beneath each of the members 34 and 36, the solid matter suspended in the excess liquid is impelled downward below the Weir level and, when the liquid has to ilow upward and over the members 35, and 37, the solids tend to continue downward due to their inertia added to gravitational forces, so that they are well below the Weir when the liquid, after the same lateral travel, approaches the yWeir edge 17. Any suspended grit which may pass the battles 35 and 36 is deflected downward by the member 37 and through the gap 49 between the member 35 and the wall ofY sump 5.

During the reforming process, the grains of the grit are eventually worn down or shattered from the violet impacts and abrasion against each other and the parts being treated. According to this invention, however, a uniform reforming of the parts continues, because the surface reforming grit, when worn down or shattered so far as to be no longer suitable for the reforming process is removed from the blasting liquid.

. 'Ihe articles after blasting in chamber 1 pass on through the ilushdown chamber 3 where the surface of each part is washed clean by high velocity streams of clear liquid ldirected through the nozzles 29 on the fiushdown manifolds 9.

Due to the breakwater action of the baille arrangement, the overilowing liquid has been brought to a quiet uniform ilow condition so that it overilows uniformly along the entire tortuous edge 17 of the weir. The excess liquid with the more readily suspended matter carried thereby after passing over the weir edge 17 ilows along the `trough 7 to the settling tank 25, from which a clear liquid overflows into the tank 24 around the pump 23.

As already mentioned above, the depth and rate of flow of the excess liquid ilowing over the weir edge 17 isV reduced by extending the weir edge with a series of pocket-like extensions 118.

These are most economically made by notcln'ng or castellating the upper edge of sump 5, and welding onto the outside face and about each such notched position the triangular pocket structure 18; The Weir edges 17 o f the pocket-like extensions 18 are disposed in the same plane as the rest of the weir edge 17 and are continuous -with those portions of the Weir edge 17 disposed therebetween. It is evident that, if desired, the pocket-like extension may be disposed along the inside face and about the notched portions to secure the same result.

In order to provide `for controlled ilow into the pockets l 18 (see FIGURE 5), :a slot 56 is provided at the bottom and the notch is left open at the top, as shown at 57. The wall 58 between may be a part of the originally formed sump tank 5, which is merely slotted at 56 and 57; Kbut it is ordinarily more economical to cut a full notch for the pocket 18 and then weld a strip 58 over the opening, spaced top and bottom as shown.

As a final precaution against overilow of valuable grit, a baille 55 may be provided, as illustrated in FIG. 5, functioning in much `the same way as baille 38.

`If suspended solids which should have been retained in the sump should enter the pocket 1S, they gravitate downward toward and through the slit 56 which communicates with the hailed area inside the periphery of the sump, and there settles toward and through the gaps 53 and 49.

Thus, it will be seen that the incorporation of the novel baille and weir system of this invention with hydraulic classification syntem of the instant type provides for a positive separation of the solids which should be retained, and with accurate gauging. Due to the smooth quiet ilow of the excess liquid to the Weir edge 17 loss of grit due to turbulence is avoided. Moreover, as the effective Weir length of the shed system can be varied by design of the pocket-like extensions 1S, this action can g be adjusted to Vthe requirements `of different grits and different input volumes of excess liquids.

We claim:

l. An apparatus -for hydraulic grit blasting of manufactored parts with liquid suspension of grit for surface re-forming of said parts, which comprises a sump with walls converging downward yto -a grit-collecting region, whereby suspended grit gravitates to said region, a liquid jet ejector in said region for entraining the settled grit in a liquid blast directed toward said part, means for holding said part with its surface -to be re-formed in the area of and transverse to said liquid blast, Ymeans for collecting the liquid, grit and removed material from an abrasive blasting operation and returning it to a central area of said sump, said sump having a tortuous top portion on its peripheral wall terminating in a weir edge, adapted to accommodate a smooth skimming over-ilow, equal to the excess liquid introduced by the ejector jet.

l2. An apparatus as deiined in claim 1 which further cmprises a gutter surrounding the sump at said weir e ge.

3. An apparatus as deilned in claim 1 which further comprises at least one baille spaced inwardly of said Weir edge, extending longitudinally of said edge and extending transversely down into said sump substantially below the level of said horizontal edge and upward substantially above said edge.

4. An apparatus as defined in claim 3 which further copirses a skimming baille inwardly of said first-named ba e. 1 5. An apparatus as defined in claim 3 which further .comprises a skimming baille and another baille extending from near the peripheral Wall of the sump substantially below the ilrst-named bafile to `approximately the liquid level in the sump and substantially inward of the ilrst named baille, whereby liquid seeking to overilow from the sump is forced to turn upward as it approaches the baille and is only allowed to ilow over said baille toward the weir edge after it has suffered a sharp reversal of ilow, whereby the suspended solids are accelerated downward in the sump while the excess liquid turns up toward the weir edge.

6. An apparatus as deilned in claim 1 which further comprises a plurality of spaced bailles in labyrinth arrangement radially, said baflles being arranged diagonally sloping downward and radially and alternate balles being transverse to one another sloping respectively inward and outward, one edge 0f each running along, but spaced from, the face of the next.

References Cited in the ille of this patent UNITED STATES PATENTS 1,692,948 `Moore Nov. 27, 1928 1,825,542 Peik Sept. 29, 1931 2,426,072 Wall et al Aug. 19, 1947 2,516,222 Lindmark July 25, 1950 2,612,731 Gladfelter et al. Gct. 7, 1952 Y 2,955,387 Soderman Oct. 11, 1960 2,995,873 Ackerman Aug. 15, 1961 3,026,789 Mead Mar. 27, 1962 3,044,218 Munn July 17, 1962 

1. AN APPARATUS FOR HYDRAULIC GRIT BLASTING OF MANUFACTURED PARTS WITH LIQUID SUSPENSION OF GRIT FOR SURFACE RE-FORMING OF SAID PARTS, WHICH COMPRISES A SUMP WITH WALLS CONVERGING DOWNWARD TO A GRIT-COLLECTING REGION, WHEREBY SUSPENDED GRIT GRAVITATES TO SAID REGION, A LIQUID JET EJECTOR IN SAID REGION FOR ENTRAINING THE SETTLED GRIT IN A LIQUID BLAST DIRECTED TOWARD SAID PART, MEANS FOR HOLDING SAID PART WITH ITS SURFACE TO BE RE-FORMED IN THE AREA OF AND TRANSVERSE TO SAID LIQUID BLAST, MEANS FOR COLLECTING THE LIQUID, GRIT AND REMOVED MATERIAL FROM AN ABRASIVE BLASTING OPERATION AND RETURNING IT TO A CENTRAL AREA OF SAID SUMP, SAID SUMP HAVING A TORTUOUS TOP PORTION ON ITS PERIPHERAL WALL TERMINATING IN A WEIR EDGE, ADAPTED TO ACCOMMODATE A SMOOTH SKIMMING OVERFLOW, EQUAL TO THE EXCESS LIQUID INTRODUCED BY THE EJECTOR JET. 